Surface chemistry modified latex and resdispersible powders, production and use thereof

ABSTRACT

The present invention relates to a latex with modified surface chemistry, which may be obtained by carrying out a free-radical emulsion polymerization in the presence of at least one ethylenically unsaturated monomer or at least one polymer containing residual ethylenically unsaturated bonds,of at least one free-radical polymerization initiator,of at least one water-soluble and/or water-dispersible monoblock, diblock or triblock polymer comprising at its end an active group capable of forming a radical, chosen from dithioesters, xanthates, thioether-thiones and diothiocarbamates. The invention similarly relates to redispersible powders that may be obtained by drying the said latices.

[0001] The present invention relates to a latex with modified surfacechemistry, and also to redispersible powders that may be obtained fromthe said latices.

[0002] The invention similarly relates to the production of latices andpowders.

[0003] Finally, the invention relates to formulations intended for usesin building materials, adhesives, paints and papers comprising thelatices or powders, and also to the use of the latices or powders insuch formulations.

[0004] Latices are products that are well known to those skilled in theart, as are the redispersible powders obtained from these latices. Theyfind many applications, especially as additives in formulations forpaints, for paper (coating mixtures, bulk paper) or in formulationsintended to be applied in the building industry (adhesive, bondingagents, smoothing coatings, etc.). They give important properties to theformulations in the composition into which they are incorporated, byvirtue, for example, of their binding power, their film-forming powerand their ability to impart particular Theological properties.

[0005] However, in the case of certain formulations such as, forexample, water-based paint formulations, it is found to be necessary tosatisfy two contradictory requirements. Thus, in these pigment-richpaint formulations, the latex used as binder must not only have goodcolloidal stability in wet paint (before drying), so as to avoid anincrease in viscosity during storage, but also, in dry form, must showgood adhesion to pigments, in order for the coat of paint to have thedesired mechanical characteristics. Now, it has been shown that one ofthe phenomena involved in increasing the viscosity on storage is the wetadsorption of the latices onto the pigments. These two properties arethus, in principle, antinomic, since, in order to satisfy the first, itis sought to reduce the latex/filler interactions, whereas these need tobe promoted in order to satisfy the second.

[0006] In general, for all the applications of latices, it is sought toreconcile good colloidal stability of the aqueous formulations beforedrying, and good water resistance after drying.

[0007] Hitherto, the solutions provided to solve the problem ofcolloidal stability consisted in introducing a sufficiently large amountof monomers during the synthesis of latices, or alternatively to grafthydrophilic macromonomers onto them. However, the presence of thesehydrophilic species has the consequence of impairing thewater-resistance properties of the final latex, and thus of harming thesecond requirement. This solution is therefore not entirelysatisfactory.

[0008] As regards redispersible powders, it should be noted that thesemust be able to be readily redispersed in aqueous media, while at thesame time conserving a certain level of insensitivity to water.Redispersible powders are generally obtained by drying latices, in thepresence of a drying adjuvant. However, although the powders thusobtained have good redispersion properties, the presence of this dryingadjuvant, which is used in large amounts (of the order- of 10 to 20%relative to the latex), is the cause of difficulty in the subsequent useof the formulations containing them. For example, in the case offormulations intended for construction applications, the presence ofthis adjuvant may result in delays in setting, a discoloration of theformulation, water sensitivity, heat sensitivity, etc.

[0009] In this case also, a satisfactory compromise remains to be found.

[0010] One of the aims of the present invention is to propose a latexwith modified surface chemistry, and redispersible powders, to solve theproblems mentioned above.

[0011] Thus, the latices according to the present invention haveincreased stability in paint formulations.

[0012] Similarly, it has been found that the redispersible powdersobtained from these latices show increased redispersibility whencompared with those obtained from latices obtained by conventionalmethods using the same monomers in the same proportions.

[0013] In addition, it has been noted, entirely unexpectedly, that theredispersible powders obtained according to the invention no longer makeit necessary to use such large amounts of drying adjuvant as thoseconventionally used to obtain a-good redispersion.

[0014] It should furthermore be noted that the latices introduced intoformulations for paints, building materials and papers have good wet anddry binding power.

[0015] These aims and others are achieved by the present invention, onesubject of which is thus a latex with modified surface chemistry, whichmay be obtained by carrying out a free-radical emulsion polymerizationin the presence:

[0016] of at least one ethylenically unsaturated monomer or at least onepolymer containing residual ethylenically unsaturated bonds,

[0017] of at least one free-radical polymerization initiator,

[0018] of at least one water-soluble and/or water-dispersible monoblock,diblock or triblock polymer comprising at its end an active groupcapable of forming a radical, chosen from dithioesters,thioether-thiones, diothiocarbamates and xanthates.

[0019] A subject of the invention is similarly redispersible powdersthat may be obtained by drying the latices.

[0020] Similarly, the invention relates to formulations intended to beapplied in building materials, in paint materials, in paper material andin adhesive and pressure-sensitive adhesive materials comprising thelatex or the redispersible powders.

[0021] Similarly, the invention relates to the use of latices andredispersible powders in formulations intended to be used in theconstruction industry and the paint industry.

[0022] However, other advantages and characteristics of the presentinvention will emerge more clearly on reading the description and theexamples that follow.

[0023] As has been mentioned previously, the process according to theinvention consists in carrying out a free-radical polymerization in thepresence of a water- soluble and/or water-dispersible monoblock, diblockor triblock polymer comprising at its end an active group capable offorming a radical, and chosen from dithioesters, thioether-thiones,dithiocarbamates and xanthates.

[0024] A polymer is considered to be water-dispersible and/orwater-soluble, according to the invention, if it shows the followingbehaviour:

[0025] 1) On a macroscopic scale:

[0026] for at least 90% of the solution/dispersion, no decantation orseparation of macroscopic phases is observed for a solution/dispersioncomprising 10 to 50% by weight of polymer, over a time scale of 7 days.

[0027] 2) On a microscopic scale:

[0028] 2.1) either the polymer does not self-associate at themicroscopic scale, and is in the form of individual chains;

[0029] 2.2) or the polymer self-associates, at the microscopic scale,locally, to form aggregates or micelles, in the manner of associativepolymers or surfactants.

[0030] In the latter case, these are not gelled structures. It isrecalled that this term means that the average residence time of anindividual chain inside this gelled structure is at least 15 minutes.

[0031] According to a first embodiment of the present invention, themonoblock, diblock or triblock polymer corresponds to the followingformula:

(R¹)x-Z¹¹-C(═S)-Z¹²-[A]-R¹²  (I)

[0032] in which formula:

[0033] Z¹¹ represents C, N, O, S or P,

[0034] Z¹² represents S or P,

[0035] R¹¹ and R¹², which may be identical or different, represent:

[0036] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup (i), or

[0037] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring (ii), or

[0038] a saturated or unsaturated, optionally substituted heterocycle(iii), these groups and rings (i), (ii) and (iii) possibly beingsubstituted with substituted phenyl groups, substituted aromatic groupsor groups: alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH),acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN), alkylcarbonyl,alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido,maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH), amino(—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl, groups ofhydrophilic or ionic nature such as the alkali metal salts of carboxylicacids, the alkali metal salts of sulphonic acid, polyalkylene oxide (PEOor PPO) chains and cationic substituents (quaternary ammonium salts),

[0039] R respresenting an alkyl or aryl group,

[0040] x corresponds to the valency of Z¹¹, or alternatively

[0041] x is 0, in which case Z¹¹ represents a phenyl, alkene or alkyneradical, optionally substituted with an optionally substituted alkyl;acyl; aryl; alkene or alkyne group; an optionally substituted,saturated, unsaturated, or aromatic, carbon-based ring; an optionallysubstituted, saturated or unsaturated heterocycle; alkoxycarbonyl oraryloxycarbonyl (—COOR); carboxyl (COOH); acyloxy (—O₂CR); carbamoyl(—CONR₂); cyano (—CN); alkylcarbonyl; alkylarylcarbonyl; arylcarbonyl;arylalkylcarbonyl; phthalimido; maleimido; succinimido; amidino;guanidimo; hydroxyl (—OH); amino (—NR₂); halogen; allyl; epoxy; alkoxy(—OR), S-alkyl; S-aryl groups; groups of hydrophilic or ionic naturesuch as the alkali metal salts of carboxylic acids, the alkali metalsalts of sulphonic acid, polyalkylene oxide (PEO or PPO) chains andcationic substituents (quaternary ammonium salts);

[0042] A represents a monoblock, diblock or triblock polymer.

[0043] According to one advantageous variant of the invention, thecompound of formula (I) is such that Z¹¹ is an oxygen atom and Z¹² is asulphur atom. These compounds are thus functionalized at the end of thechain with xanthates.

[0044] As regards the polymer A, it corresponds more particularly to atleast one of the three formulae below:

[0045] in which formulae:

[0046] Va, V′a, Vb, V′b, Vc and V′c, which may be identical ordifferent, represent: H, an alkyl group or a halogen,

[0047] Xa, X′a, Xb, X′b, Xc and X′c, which may be identical ordifferent, represent H, a halogen or a group R, OR, OCOR, NHCOH, OH,NH2, NHR, N(R)₂, (R)₂N⁺O⁻, NHCOR, CO₂H, CO₂R, CN, CONH₂, CONHR or CONR₂,in which R, which may be identical or different, are chosen from alkyl,aryl, aralkyl, alkaryl, alkene and organosilyl groups, optionallyperfluorinated and optionally substituted with one or more carboxyl,epoxy, hydroxyl, alkoxy, amino, halogen or sulphonic groups,

[0048] l, m and n, which may be identical or different, are greater thanor equal to 1,

[0049] x, y and z, which may be identical or different, are equal to 0or 1.

[0050] More particularly, the polymer A is obtained by using at leastone ethylenically unsaturated monomer chosen from hydrophilic monomers.

[0051] Examples of such monomers that may especially be mentionedinclude

[0052] ethylenically unsaturated monocarboxylic and dicarboxylic acids,for instance acrylic acid, methacrylic acid, itaconic acid, maleic acidor fumaric acid,

[0053] monoalkyl esters of dicarboxylic acids of the type mentioned withalkanols preferably containing 1 to 4 carbon atoms, and N-substitutedderivatives thereof, such as, 2-hydroxyethyl acrylate or methacrylate,

[0054] unsaturated carboxylic acid amides, for instance acrylamide ormethacrylamide,

[0055] ethylenic monomers comprising a sulphonic acid group and amoniumor alkali metal salts thereof, for example vinylsulphonic acid,vinylbenzenesulphonic acid, α-acrylamidomethylpropanesulphonic acid or2-sulphoethylene methacrylate.

[0056] Needless to say, it is possible to incorporate into the polymercomposition a proportion of hydrophobic monomers, provided that thesolubility/dispersity conditions and the conditions of non-formation ofgelled or non-gelled micelles, mentioned previously, remain valid.

[0057] Illustrations of hydrophobic monomers that may especially bementioned include styrene or its derivatives, butadiene, chloroprene,(meth)acrylic esters, vinyl esters and vinyl nitriles.

[0058] The term “(meth)acrylic esters” denotes esters of acrylic acidand of methacrylic acid with hydrogenated or fluorinated C₁-C₁₂ andpreferably C₁-C₈ alcohols. Among the compounds of this type that may bementioned are: methyl acrylate, ethyl acrylate, propyl acrylate, n-butylacrylate, isobutyl acrylate, 2-ethylhexyl acrylate, t-butyl acrylate,methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutylmethacrylate.

[0059] The vinyl nitriles more particularly include those containingfrom 3 to 12 carbon atoms, such as, in particular, acrylonitrile andmethacrylonitrile.

[0060] It should be noted that the styrene may be totally or partiallyreplaced with derivatives such as α-methylstyrene or vinyltoluene.

[0061] The other ethylenically unsaturated monomers that may be used,alone or as mixtures, or that are copolymerizable with the abovemonomers are especially:

[0062] vinyl esters of a carboxylic acid, for instance vinyl acetate,vinyl versatate or vinyl propionate,

[0063] vinyl halides,

[0064] vinylamine amides, especially vinylformamide or vinylacetamide,

[0065] ethylenically unsaturated monomers comprising a secondary,tertiary or quaternary amino group, or a heterocyclic group containingnitrogen, such as, for example, vinylpyridines, vinylimidazole,aminoalkyl (meth)acrylates and aminoalkyl(meth)acrylamides, for instancedimethylaminoethyl acrylate or methacrylate, di-tert-butylaminoethylacrylate or methacrylate, dimethylaminomethylacrylamide ordimethylaminomethylmethacrylamide. It is likewise possible to usezwitterionic monomers such as, for example, sulphopropyl(dimethyl)aminopropyl acrylate.

[0066] According to one particularly advantageous embodiment, thepolymer A is a monoblock or a diblock polymer.

[0067] It should moreover be noted that the polymer A more particularlyhas a number-average molar mass of less than 20 000 and preferably lessthan 10 000. These molar masses are measured by steric exclusionchromatography, using polyethylene glycol as standard.

[0068] This type of monoblock, diblock or triblock polymer containing areactive end is known to those skilled in the art and has especiallybeen the subject of patent applications WO 98/58974 and WO 99/35178.

[0069] Reference may thus be made to the description of these two patentapplications for the preferred definitions of the various groups andradicals, and similarly for their preparation.

[0070] According to a second embodiment of the invention, the monoblock,diblock or triblock polymer used is a polymer corresponding to thefollowing formulae:

[0071] in which formulae:

[0072] X represents an atom chosen from N, C, P and Si,

[0073] R²² represents:

[0074] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup (i), or

[0075] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring (ii), or

[0076] a saturated or unsaturated, optionally substituted or aromaticheterocycle (iii), these groups and rings (i), (ii) and (iii) possiblybeing substituted with substituted phenyl groups, substituted aromaticgroups or groups: alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl(—COOH), acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN),alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl,phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH),amino (—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl,organosilyl, groups of hydrophilic or ionic nature such as the alkalimetal salts of carboxylic acids, the alkali metal salts of sulphonicacid, polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts), R representing an alkyl or aryl group,

[0077] Z, R^(21i) and R²³, which may be identical or different, arechosen from:

[0078] a hydrogen atom,

[0079] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup,

[0080] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring,

[0081] a saturated or unsaturated, optionally substituted heterocycle,

[0082] alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH),acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN), alkylcarbonyl,alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido,maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH), amino(—NR2), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl andorganosilyl groups, R representing an alkyl or aryl group,

[0083] groups of hydrophilic or ionic nature such as the alkali metalsalts of carboxylic acids, the alkali metal salts of sulphonic acid,polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts).

[0084] n>0,

[0085] i ranges from 1 to n,

[0086] p is equal to 0, 1 or 2 depending on the valency of X,

[0087] and also

[0088] if X═C, then Z is not an S-alkyl or S-aryl group,

[0089] the group R^(1i), where i=n, is not an S-alkyl or S-aryl group,

[0090] A represents a monoblock, diblock or triblock polymer as definedpreviously.

[0091] The definition of the polymer A described in the case of thefirst variant remains valid and will not be repeated here. Reference maythus be made entirely thereto.

[0092] According to a third embodiment of the invention, the monoblock,diblock or triblock polymer used is a polymer corresponding to thefollowing formula:

[0093] in which formula:

[0094] X represents an atom chosen from N, C, P and Si,

[0095] R³² represents:

[0096] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup (i), or

[0097] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring (ii), or

[0098] a saturated or unsaturated, optionally substituted or aromaticheterocycle (iii), these groups and rings (i), (ii) and (iii) possiblybeing substituted with substituted phenyl groups, substituted aromaticgroups or groups: alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl(—COOH), acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN),alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl,phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH),amino (—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl,organosilyl, groups of hydrophilic or ionic nature such as the alkalimetal salts of carboxylic acids, the alkali metal salts of sulphonicacid, polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts),

[0099] R representing an alkyl or aryl group,

[0100] Z is chosen from:

[0101] a hydrogen atom,

[0102] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup,

[0103] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring,

[0104] a saturated or unsaturated, optionally substituted heterocycle,

[0105] alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH),acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN), alkylcarbonyl,alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido,maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH), amino(—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl andorganosilyl groups, R representing an alkyl or aryl group,

[0106] groups of hydrophilic or ionic nature such as the alkali metalsalts of carboxylic acids, the alkali metal salts of sulphonic acid,polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts)

[0107] R³¹, which may be identical or different, are chosen from:

[0108] a hydrogen atom,

[0109] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup,

[0110] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring,

[0111] a saturated or unsaturated, optionally substituted heterocycle,

[0112] alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH),acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN), alkylcarbonyl,alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido,maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH), amino(—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl andorganosilyl groups, R representing an alkyl or aryl group,

[0113] groups of hydrophilic or ionic nature such as the alkali metalsalts of carboxylic acids, the alkali metal salts of sulphonic acid,polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts),

[0114] groups SR³²,

[0115] n>0.

[0116] The definition of the polymer A described in the case of thefirst variant remains valid and will not be repeated here. Reference maythus be made entirely thereto.

[0117] According to a fourth embodiment of the invention, the monoblock,diblock or triblock polymer used corresponds to the following formula:

S═C(Z)-[C≡C]n—S-[A]-R⁴¹  (IV)

[0118] in which formula:

[0119] R⁴¹ represents:

[0120] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup (i), or

[0121] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring (ii), or

[0122] a saturated or unsaturated, optionally substituted or aromaticheterocycle (iii), these groups and rings (i), (ii) and (iii) possiblybeing substituted with substituted phenyl groups, substituted aromaticgroups or groups: alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl(—COOH), acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN),alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl,phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH),amino (—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl,organosilyl, groups of hydrophilic or ionic nature such as the alkalimetal salts of carboxylic acids, the alkali metal salts of sulphonicacid, polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts), R representing an alkyl or aryl group,

[0123] Z, which may be identical or different, are chosen from:

[0124] a hydrogen atom,

[0125] an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup,

[0126] a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring,

[0127] a saturated or unsaturated, optionally substituted heterocycle,

[0128] alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH),acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN), alkylcarbonyl,alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido,maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH), amino(—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl andorganosilyl groups, R representing an alkyl or aryl group,

[0129] groups of hydrophilic or ionic nature such as the alkali metalsalts of carboxylic acids, the alkali metal salts of sulphonic acid,polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts),

[0130] n>0.

[0131] The definition of the polymer A described in the case of thefirst variant remains valid and will not be repeated here. Reference maythus be made entirely thereto.

[0132] The polymers (IIa), (IIb) (III) and (IV) may be obtained byplacing in contact at least one ethylenically unsaturated monomer, atleast one source of free radicals and at least one compound of formula(A), (B) or (C)

S═C(Z)-[C≡C]_(n)-S—R⁴¹  (C)

[0133] Generally, these polymers have a polydispersity index of not morethan 2 and preferably not more 1.5.

[0134] The production of the diblock or triblock polymers consists inrepeating the implementation of the polymerization process describedabove one or two times, using:

[0135] monomers different from the previous implementation, and

[0136] in place of the compound of formula (A), (B) or (C), the blockpolymer obtained from the previous implementation, known as theprecursor polymer.

[0137] Optionally, it may be desired to place blocks of controlledpolydispersity at the surface of the latices. In this case, severalsolutions of monoblock, diblock and/or triblock polymer, each having awell-defined molecular mass, may be mixed together in specificproportions.

[0138] According to this process for preparing multiblock polymers, whenit is desired to obtain polymers with homogeneous blocks rather thanwith a composition gradient, and when all the successive polymerizationsare performed in the same reactor, it is essential for all the monomersused during one step to have been consumed before the polymerization ofthe following step commences, and thus before the new monomers areintroduced.

[0139] As for the process for polymerizing monoblock polymer, thisprocess for polymerizing block polymers has the advantage of leading toblock polymers with a low polydispersity index. It also makes itpossible to control the molecular mass of the block polymers.

[0140] The block polymers corresponding to formulae (II) to (IV) havebeen the subject of a French patent application No. FR 99/07097.

[0141] It should be noted that the principles for preparing monoblock,diblock and triblock polymers applied to these three variants of theinvention may be extrapolated to the other polymer variants according tothe invention.

[0142] According to a fifth embodiment of the invention, the monoblock,diblock or triblock polymer used corresponds to the following formula:

S═C(OR⁵¹)—S-[A]-R⁵²  (V)

[0143] in which formula:

[0144] R⁵¹ represents:

[0145] in which:

[0146] R⁵³ and R⁵⁴ which may be identical or different, are chosen fromhalogen, =O, ═S, —NO₂, —SO₃R, NCO, CN, OR, —SR, —NR₂, —COOR, O₂CR,—CONR₂ and —NCOR₂ groups with R representing a hydrogen atom or an alkylradical, alkenyl radical, alkynyl radical, cycloalkenyl radical,cycloalkynyl radical, aryl radical optionally fused to an aromatic ornon- aromatic heterocycle, alkylaryl radical, aralkyl radical orheteroaryl radical; these radicals may optionally be substituted withone or more groups, that may be identical or different, chosen fromhalogens, ═O, ═S, OH, alkoxy, SH, thioalkoxy, NH₂, monoalkylamino,dialkylamino, CN, COOH, ester, amide and CF₃ and/or optionallyinterrupted with one or more atoms chosen from O, S, N and P; or from aheterocyclic group optionally substituted with one or more groups asdefined above; or R⁵³ and R⁵⁴ form, together with the carbon atom towhich they are attached, a hydrocarbon-based ring or a heterocycle;

[0147] R⁵³ and R⁵⁶, which may be identical or different, represent agroup as defined above for R; or together form a C₂-C₄ hydrocarbon-basedchain, optionally interrupted with a hetero atom chosen from O, S and N;

[0148] R⁵² has the same definition as that given for R⁵³;

[0149] A represents a monoblock, diblock or triblock polymer.

[0150] According to one preferred variant, the groups R⁵³ are chosenfrom —CF₃, —CF₂CF₂CF₃, CN and NO₂.

[0151] Advantageously, R⁵⁴ represents a hydrogen atom.

[0152] The radicals R⁵⁵ and R⁵⁶, which may be identical or different,represent an alkyl radical, preferably a C₁-C₆ alkyl radical.

[0153] The polymers of formula (V) may be obtained by placing in contactat least one ethylenically unsaturated monomer, at least one source offree radicals and at least one compound of the following formulae:

S═C(OR⁵¹)-S-R⁵²  (A′)

R′⁵¹—(O—C(═S)—R⁵²)p  (B′)

R′⁵¹-(S—C(═S)—O—R⁵¹)p  (C′)

[0154] in which formulae:

[0155] R⁵¹ and R′⁵¹, which may be identical or different, have the samedefinition as that given previously for R⁵¹,

[0156] R⁵² and R′⁵², which may be identical or different, have the samemeaning as that given previously for R⁵²,

[0157] p represents an integer between 2 and 10.

[0158] The compounds of formula (A′) may especially be obtained byreacting a carbonyl compound of formula R⁵³—C(═O)—R⁵⁴ with a phosphiteof formula (R⁵⁵O)HP(═O)(OR⁵⁶). The resulting compound may then be placedin contact with carbon disulphide in the presence of an alkoxide, andthen with a halide R⁵²—X.

[0159] The compounds of formulae (B′) and (C′) may be obtained by usingan equivalent principle, but starting with polyhydroxylated compounds.

[0160] The ethylenically unsaturated monomers used to produce the latexwill now be described.

[0161] Among the suitable monomers that may be mentioned mostparticularly are those corresponding to the following formula:

CXdX′d(═CVd-CV′d)_(t)═CH₂

[0162] Xd and X′d, which may be identical or different, represent: H, analkyl group or a halogen,

[0163] Vd and V′d, which may be identical or different, represent H, ahalogen or a group R, OR, OCOR, NHCOH, OH, NH₂, NHR, N(R)₂, (R)₂N⁺O⁻,NHCOR, CO₂H, CO₂R, CN, CONH₂, CONHR or CONR₂, in which R, which may beidentical or different, are chosen from alkyl, aryl, aralkyl, alkaryl,alkene and organosilyl groups, optionally perfluorinated and optionallysubstituted with one or more carboxyl, epoxy, hydroxyl, alkoxy, amino,halogen or sulphonic groups,

[0164] t is 0 or 1.

[0165] According to one particular embodiment of the invention, themonomers used are preferably hydrophobic monomers.

[0166] As illustrations of hydrophobic monomers, mention may be madeespecially of styrene or its derivatives, butadiene, choroprene,(meth)acrylic esters, vinyl esters and vinyl nitriles.

[0167] The term “(meth)acrylic esters” denotes esters of acrylic acidand of methacrylic acid with hydrogenated or fluorinated C₁-C₁₂ andpreferably C₁-C₈ alcohols.

[0168] The vinyl nitrites more particularly include those containingfrom 3 to 12 carbon atom such as, in particular, acrylonitrile andmethacrylonitrile.

[0169] It should be noted that the styrene can be replaced totally orpartially with derivatives such as α-methylstyrene or toluene.

[0170] The other ethylenically unsaturated monomers that may be used,alone or as mixtures, or that are copolymerizable with the abovemonomers are especially:

[0171] vinyl esters of carboxylic acids,

[0172] vinyl halides,

[0173] vinylamine amides,

[0174] ethylenically unsaturated monomers comprising a secondary,tertiary or quaternary amino group, or a heterocyclic group containingnitrogen. It is similarly possible to use zwitterionic monomers such as,for example, sulphopropyl (dimethyl)aminopropyl acrylate.

[0175] It should be noted that it is possible to use hydrophilicmonomers such as, for example

[0176] ethylenically unsaturated monocarboxylic and dicarboxylic acids,

[0177] monoalkyl esters of dicarboxylic acids of the type mentioned withalkanols preferably containing 1 to 4 carbon atoms, and N-substitutedderivatives thereof,

[0178] amides of unsaturated carboxylic acids,

[0179] ethylenic monomers comprising a sulphonic acid group and itsammonium or alkali metal salts,

[0180] unsaturated carboxylic acid amides, for instance acrylamide,methacrylamide, N-methylolacrylamide or N-methylolmethacrylamide, andN-acrylamides.

[0181] It should be noted that all the monomers that have been mentionedin the context of the definition of the monoblock, diblock or triblockpolymer may be used to obtain the latex. Reference may thus be made tothis section of the description.

[0182] It should be noted that the ethylenically unsaturated monomerpreferably used is at least one monomer chosen from styrene or itsderivatives, butadiene, chloroprene, (meth)acrylic esters, vinyl estersand vinyl nitriles.

[0183] As regards the second possibility, which consists in using apolymer containing residual ethylenically unsaturated bonds, thispolymer is obtained by free-radical polymerization of at least oneethylenically unsaturated monomer chosen from:

CXdX′d(═CVd-CV′d)_(t)═CH₂

[0184] Xd and X′d, which may be identical or different, represent: H, analkyl group or a halogen,

[0185] Vd and V′d, which may be identical or different, represent H, ahalogen or a group R, OR, OCOR, NHCOH, OH, NH₂, NHR, N(R)₂, (R)₂N⁺O⁻,NHCOR, CO₂H, CO₂R, CN, CONH₂, CONHR or CONR₂, in which R, which may beidentical or different, are chosen from alkyl, aryl, aralkyl, alkaryl,alkene and organosilyl groups, optionally perfluorinated and optionallysubstituted with one or more carboxyl, epoxy, hydroxyl, alkoxy, amino,halogen or sulphonic groups,

[0186] t is 0 or 1.

[0187] The polymerization reaction according to the invention takesplace in the presence of a free-radical polymerization initiator Thismay be chosen from the initiators conventionally used in free-radicalpolymerization. It may be, for example, one of the following initiators:

[0188] hydrogen peroxides such as: tert-butyl hydroperoxide, cumenehydroperoxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butylperoxyoctoate, t-butyl peroxyneodecanoate, t-butyl peroxyisobutarate,lauroyl peroxide, t-amyl peroxypivalate, t-butyl peroxypivalate, dicumylperoxide, benzoyl peroxide, potassium persulphate, ammonium persulphate,

[0189] azo compounds such as:

[0190] 2,2′-azobis(isobutyronitrile), 2,2′-azobis(2-butane-nitrile,4,4′-azobis(4-pentanoic acid), 1,1′-azobis(cyclohexanecarbonitrile),2-(t-butylazo)-2-cyanopropane,2,2′-azobis[2-methyl-N-(1,1)-bis(hydroxymethyl)-2-hydroxyethyl]propionamide,2,2′-azobis(2-methyl-N-hydroxyethyl]propionamide,2,2′-azobis(N,N′-dimethyleneisobutyramidine) dichloride,2,2′-azobis(2-amidinopropane) dichloride,2,2′-azobis(N,N′-dimethyleneisobutyramide),2,2′-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide),2,2′-azobis[2-methyl-N-1,1-bis(hydroxymethyl)-ethyl]propionamide,2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2′-azobis(isobutyramide) dihydrate,

[0191] redox systems comprising combinations such as: βmixtures ofhydrogen peroxide, of alkyl, peresters, percarbonates and the like andof any of the iron salts, titanous salts, zinc formaldehyde sulphoxylateor sodium formaldehyde sulphoxylate, and reducing sugars,

[0192] ammonium or alkali metal persulphates, perborate or perchloratein combination with an alkali metal bisulphite, such as sodiummetabisulphite, and reducing sugars,

[0193] alkali metal persulphates in combination with an arylphosphinicacid, such as benzenephosphonic acid and the like, and reducing sugars.

[0194] The polymerization reaction takes place conventionally.

[0195] It is carried out in the presence of a nonionic or anionicsurfactant chosen from alkoxylated mono-, di- or trialkylphenols,alkoxylated mono-, di- or tristyrylphenols, alkoxylated fatty alcoholsand ammonium or alkali metal salts of C₈-C₁₂ alkyl sulphates,alkoxylated sulphated fatty alcohol semiesters, C₁₂-C₁₈ alkyl sulphonateesters, etc.

[0196] The polymerization temperature is also conventional. By way ofillustration, the temperature is between 50 and 120° C. and moreparticularly between 70 and 100° C.

[0197] Thus, a first embodiment of the polymerization consists incarrying out this polymerization by introducing the ethylenicallyunsaturated monomer and the initiator into a solution of monoblock,diblock or triblock polymer.

[0198] According to a second embodiment of the polymerization, it iscarried out by introducing in parallel the ethylenically unsaturatedmonomer, the initiator and a solution of monoblock, diblock or triblockpolymer.

[0199] According to a third embodiment, the polymerization is performedby introducing the monoblock, diblock or triblock polymer and theinitiator into a suspension comprising the polymer containing residualethylenically unsaturated bonds.

[0200] Another subject of the present invention consists ofredispersible powders that may be obtained by drying the latex ofmodified surface chemistry.

[0201] The drying may be performed in a manner that is known per se.

[0202] Thus, a drying at low temperature or, preferably, by spraying,may be carried out.

[0203] It may be carried out in any known device such as, for example, aspraying tower combining spraying performed via a nozzle or a turbomixerwith a stream of hot gas.

[0204] The inlet temperature of the hot gas (generally air), at the topof the column, is preferably between 100 and 115° C. and the outlettemperature is preferably between 55 and 65° C.

[0205] According to one advantageous embodiment of the presentinvention, the drying is performed in the presence of a drying adjuvant.

[0206] Standard dispersants may be used. For example, mention may bemade of polyphenols, glutamic acid salts, polyvinyl alcohol,polyvinylpyrrolidone or cellulose derivatives. It should be noted that anonionic or anionic surfactant may also be used.

[0207] In a particularly advantageous manner, the content of dryingadjuvant is less than or equal to 5% by weight relative to the polymer.

[0208] The latices and redispersible powders that form the subject ofthe present invention may be used in the conventional fields of use,such as in the field of building materials, of paints, of paper and ofadhesives, that may or may not be pressure-sensitive, inter alia.

[0209] Thus, a subject of the present invention is similarlyformulations intended for applications in the building materialsindustry, comprising the latex of modified surface chemistry, or theredispersible powders.

[0210] The invention also relates to formulations intended forapplications in the field of paints, comprising the latex, or theredispersible powders.

[0211] Finally, it relates to formulations intended for applications inthe field of adhesives and of pressure-sensitive adhesives, comprisingthe latex or the redispersible powders.

[0212] Concrete but non-limiting examples of the invention will now begiven.

EXAMPLES 1

[0213] These examples illustrate the preparation of monoblock anddiblock polymers according to the invention.

Example 1.1 Preparation of a Polyacrylic Acid Monoblock PolymerComprising a Reactive End of Xanthate Type (Polymer 1.1)

[0214] The following mixture is introduced into a reactor equipped witha magnetic stirrer and a reflux column, and comprising 160 g of acetone:

[0215] 16.64 g of methylisopropyl O-ethylxanthate (referred tohereinbelow as xanthate)

[0216] 63.36 g of acrylic acid,

[0217] 2 g of azobisisobutyronitrile.

[0218] The mixture is then stirred and maintained at reflux at 72° C.for 17 hours, and then cooled.

[0219] A transparent gel with a number-average molar mass of 1 050 and apolydispersity index of 1.2 (measured by GPC in water using polyethyleneglycol as standard) is obtained.

Example 1.2 Preparation of a Polyacrylic Acid/Polybutyl Acrylate DiblockPolymer Comprising a Reactive End of Xanthate Type (Polymer 1.2)

[0220] 35 g of an aqueous solution comprising 20.16 g of the polymerobtained above are placed in a conical reactor equipped with a magneticstirrer and a reflux column.

[0221] 15.5 g of acetone and 10 g of water are then introduced via thecondenser and the mixture is heated with stirring at 75° C.

[0222] 10.5 g of butyl acrylate are then introduced over 6 hours, whilekeeping the temperature at 75° C.

[0223] The temperature is maintained for 12 hours after the end of theintroduction.

[0224] The resulting product is soluble in water at pH 6 and roomtemperature.

[0225] 10.5 g of butyl acrylate are then added according to theprocedure indicated previously.

[0226] The final product has a number-average molar mass of about 2 000,i.e. p(acrylic acid: Mn=1 050)−p(butyl acrylate; Mn=1 000).

[0227] The solids content of this polymer is 51%.

Example 1.3 Preparation of a Polyacrylamide Acid Diblock PolymerComprising a Reactive End of Xanthate Type (Polymer 1.3)

[0228] The following are introduced into a reactor equipped with amagnetic stirrer and a reflux column:

[0229] 21 g of xanthate

[0230] 2.1 g of azobisisobutyronitrile

[0231] 100 g of solvent (90% ethanol/10% water)

[0232] The mixture is then stirred and heated to reflux at 75° C.

[0233] 200 g of acrylamide and 200 g of solvent (40% ethanol/60% water)are then added over 5 hours.

[0234] The resulting mixture is then maintained at 75° C. with stirringfor 1 hour, and is then cooled.

[0235] A transparent gel with a number-average molar mass of 1 050 and apolydispersity index of 1 (measured by GPC in water using polyethyleneglycol as standard) is obtained.

EXAMPLES 2

[0236] These examples illustrate the preparation of latices comprisingthe monoblock and diblock polymers according to the invention, and alsothe preparation of latices by carrying out standard techniques(comparative latices)

[0237] Procedure for Preparing the Latices

[0238] 45 g of deionized water, 600 ppm of Abex® 2020 (mixture ofethoxylated fatty alcohol and of sulphated ethoxylated fatty alcohol,sold by Rhodia—amount based on the monomer) and 1.9 g of carboxylicmonomer or polymer (their nature, which varies according to theexamples, will be specified in the tables that follow) are placed in areactor equipped with a magnetic stirrer and a reflux column.

[0239] The mixture is neutralized to a pH of between 6-7 with 20% sodiumhydroxide solution

[0240] The mixture is heated to 60° C. with stirring.

[0241] Separately, a monomer pre-emulsion is prepared in the followingmanner:

[0242] 47.5 g of deionized water, 2.6 g of carboxylic monomer orpolymer, 79.7 g of core monomers (the relative proportion of which,which varies according to the examples, will be given in the tables thatfollow) are mixed together.

[0243] The pre-emulsion is neutralized to a pH of between 6 and 7 with20% sodium hydroxide solution.

[0244] 20 g of the abovementioned pre-emulsion are rapidly added to themixture at 60° C., followed by 0.17 g of sodium persulphate dissolved in2 g of deionized water.

[0245] After addition of the pre-emulsion, the mixture is heated at80-85° C. for 45 minutes. Once the temperature has stabilized, theremainder of the pre- emulsion is added over 3 hours. After one and ahalf hours, 50 g of water are added over one and a half hours.

[0246] The resulting latex is maintained at 85° C. for 30 minutes,followed by addition of 1 000 ppm of tert-butyl peroxybenzoate and 1 000ppm of sodium metabisulphite.

[0247] The latex is then stripped.

[0248] The latex obtained has a solids content of 34.7%.

Example 2.1 Emulsion Polymerization of Styrene and of Butyl Acrylate inthe Presence of Polymer 1.1 (Latex 2.1)

[0249] Core monomers: Butyl acrylate: 60.1% Styrene: 36.9% Carboxylicpolymer: Polymer 1.1:   3%

Example 2.2 Emulsion Polymerization of Styrene and of Butyl Acrylate inthe Presence of Polymer 1.2 (Latex 2.2)

[0250] Core monomers: Butyl acrylate: 62.2% Styrene: 36.5% Carboxylicpolymer: Polymer 1.2:  1.3%

[0251] The mean diameter of the particles is 60 nm.

[0252] It should be noted that the latex flocculates at a pH of 3. Thisindicates that the latex bears polyacrylic acid-polybutyl acrylategrafts, concentrated at the surface of the particles.

Example 2.3 Emulsion Polymerization of Styrene and of Butyl Acrylate inthe Presence of Polymer 1.3 (Latex 2.3)

[0253] Core monomers: Butyl acrylate: 61% Styrene: 36% Carboxylicpolymer: Polymer 1.3:  3%

Example 2.4 Emulsion Polymerization of Styrene and of Butyl Acrylate inthe Presence of Polymer 1.1 (Latex 2.4)

[0254] Core monomers: Butyl acrylate:   60% Styrene: 36.5% Carboxylicmonomer and polymer: Itaconic acid:   1% Polymer 1.1:  2.5%

Example 2.5 Standard Free-Radical Emulsion Polymerization (ComparativeLatex 2.1)

[0255] Core monomers: Butyl acrylate: 61% Styrene: 36% Carboxylicmonomer: Acrylic acid:  3%

Example 2.6 Standard Free-Radical Emulsion Polymerization (ComparativeLatex 2.3)

[0256] Core monomers: Butyl acrylate: 61% Styrene: 36% Carboxylicmonomer: Acrylamide:  3%

Example 2.7 Emulsion Polymerization of Styrene and of Butyl Acrylate inthe Presence of Polymer 1.1 (Comparative Latex 2.4)

[0257] Core monomers: Butyl acrylate:   60% Styrene: 36.5% Carboxylicmonomers: Itaconic acid:   1% Acrylic acid:  2.5%

EXAMPLES 3

[0258] The aim of these examples is to show the properties ofredispersion of a latex film deposited on glass.

Example 3.1 Use of Glutamic Acid Salt:

[0259] Latices Tested:

[0260] Latex 2.1

[0261] Comparative latex 2.1

[0262] Method:

[0263] Two batches are prepared for each of the two latices.

[0264] The first is dried without addition of a drying adjuvant and thesecond is dried in the presence of 5% by weight, relative to the latexpolymer, of glutamic acid sodium salt.

[0265] A film 100 μm thick is deposited with each of these compositionsand the whole is dried for 15 minutes at 120° C.

[0266] The results are collated in the table below Latex Without With2.1 0 9 2.1 comparative 0 0

[0267] The grades range from 0 (no redispersion) to 10 (totalredispersion), according to a test which consists in placing a smallamount of water at the surface of the film and in judging the quality ofthe dispersion after a few seconds.

[0268] The influence of the latices on the properties of redispersion ofthe dried film are seen without question. It may furthermore be notedthat the contents of drying adjuvant are lower than those generally usedin the prior art (about 15% in general, for latices of equivalent size,i.e. about 100 to 150 mm).

Example 3.2 Use of Tannin

[0269] Latices tested:

[0270] Latex 3.1

[0271] Comparative latex 3.1

[0272] Method:

[0273] The process is performed as for Example 3.1, except that the 5%of glutamic acid salt are replaced with 5% by weight, relative to thelatex polymer, of Albatan GNL (tannin sold by Rhodia).

[0274] The results are collated in the table below Latex Without With3.1 6 10 3.1 comparative 0 10

[0275] The grades range from 0 (no redispersion) to 10 (totalredispersion).

[0276] The advantage of using latices in accordance with the inventionis once again evident, given the noteworthy changes in the redispersionproperties.

EXAMPLE 4

[0277] The aim of this example is to show the wet abrasion resistance ofa film of latex obtained according to the invention, and of a latexobtained by using a standard free-radical polymerization, these twofilms comprising calcium carbonate.

[0278] Latices tested:

[0279] Latex 2.1

[0280] Latex 2.2

[0281] Comparative latex 2.1

[0282] Preparation of the Compositions Tested:

[0283] The latices are mixed with Carbital 90 at a rate of 10 parts forthe latex and 100 parts for the Carbital 90.

[0284] Carbital 90 is an aqueous suspension of calcium carbonate.

[0285] The solids content of the compositions is adjusted to 72.5% andthe pH to 8.5.

[0286] The compositions are left to stand for 24 hours before beingapplied.

[0287] Wet Abrasion Test

[0288] (1) Manufacture of the Films

[0289] The mixtures are deposited on a support (known as “Lenetta”)using a film drawer having a gap 275 μm thick.

[0290] The drying is carried out according to the following procedure(accelerated procedure):

[0291] 24 hours in a conditioned room

[0292] 24 hours at 55° C.

[0293] 24 hours in a conditioned room

[0294] (2) Wet Abrasion Test

[0295] The dried compositions are worn in the presence of a mixture ofwater and surfactant, using a brush which automatically carries outto-and-fro motions.

[0296] The number of cycles beyond which the paint, that has been wornaway, allows the support to show through is recorded.

[0297] This test complies with standard MO 223VU013.

[0298] (3) Results Composition Number of cycles 2.1 >5 000 2.3 4 300 2.1comparative 545

EXAMPLE 5

[0299] The aim of this example is to assess the stability on storage ofcompositions comprising a latex and calcium carbonate.

[0300] Latices Tested:

[0301] Latex 2.4

[0302] Comparative latex 2.4

[0303] Preparation of the Compositions Tested:

[0304] The latices are mixed with Carbital 90 at a rate of 10 parts forthe latex and 100 parts for the Carbital 90.

[0305] Carbital 90 is an aqueous suspension of calcium carbonate.

[0306] The solids content of the compositions is adjusted to 72.5% andthe pH to 8.5.

[0307] The compositions are left to stand for 24 hours before beingapplied.

[0308] Measurement of the Viscosity:

[0309] The viscosity values are measured (at 32 second⁻¹) before andafter storage, for 3 days at 55° C. (Carri-Med CSL² 100 TA Instrumentsrheometer. These are flow viscosities under- shear in cone/plategeometry).

[0310] The results are collated in the table below: Viscosity (mPa · s)Composition Before After 2.4 494 545 2.4 comparative 290 2 876

[0311] It is clearly seen that the composition comprising the latexaccording to the invention is more stable than that obtained using astandard free-radical polymerization.

1. Latex with modified surface chemistry, which may be obtained bycarrying out a free-radical emulsion polymerization in the presence: ofat least one ethylenically unsaturated monomer or at least one polymercontaining residual ethylenically unsaturated bonds, of at least onefree-radical polymerization initiator, of at least one water-solubleand/or water-dispersible monoblock, diblock or triblock polymercomprising at its end an active group capable of forming a radical,chosen from dithioesters, thioether-thiones, diothiocarbamates andxanthates.
 2. Latex according to the preceding claim, characterized inthat the free-radical polymerization is carried out in the presence of apolymer corresponding to the following formula:(R¹¹)x-Z¹¹-C(═S)-Z¹²-[A]-R¹²  (I) in which formula: Z¹¹ represents C, N,O, S or P, Z¹² represents S or P, R¹¹ and R¹², which may be identical ordifferent, represent: an optionally substituted alkyl, acyl, aryl,alkene or alkyne group (i), or a saturated or unsaturated, optionallysubstituted or aromatic carbon-based ring (ii), or a saturated orunsaturated, optionally substituted heterocycle (iii), these groups andrings (i), (ii) and (iii) possibly being substituted with substitutedphenyl groups, substituted aromatic groups or groups: alkoxycarbonyl oraryloxycarbonyl (—COOR), carboxyl (—COOH), acyloxy (—O₂CR) carbamoyl(—CONR₂), cyano (—CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl,arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino,guanidimo, hydroxyl (—OH), amino (—NR₂), halogen, allyl, epoxy, alkoxy(—OR), S-alkyl, S-aryl, groups of hydrophilic or ionic nature such asthe alkali metal salts of carboxylic acids, the alkali metal salts ofsulphonic acid, polyalkylene oxide (PEO or PPO) chains and cationicsubstituents (quaternary ammonium salts), R respresenting an alkyl oraryl group, x corresponds to the valency of Z¹¹, or alternatively x is0, in which case Z¹¹ represents a phenyl, alkene or alkyne radical,optionally substituted with an optionally substituted alkyl; acyl; aryl;alkene or alkyne group; an optionally substituted, saturated,unsaturated, or aromatic, carbon-based ring; an optionally substituted,saturated or unsaturated heterocycle; alkoxycarbonyl or aryloxycarbonyl(—COOR); carboxyl (—COOH); acyloxy (—O₂CR); carbamoyl (—CONR₂); cyano(—CN); alkylcarbonyl; alkylarylcarbonyl; arylcarbonyl;arylalkylcarbonyl; phthalimido; maleimido; succinimido; amidino;guanidimo; hydroxyl (—OH); amino (—NR₂); halogen; allyl; epoxy; alkoxy(—OR), S-alkyl; S-aryl groups; groups of hydrophilic or ionic naturesuch as the alkali metal salts of carboxylic acids, the alkali metalsalts of sulphonic acid, polyalkylene oxide (PEO or PPO) chains andcationic substituents (quaternary ammonium salts); A represents amonoblock, diblock or triblock polymer.
 3. Latex according to claim 1,characterized in that the polymerization is carried out in the presenceof a polymer corresponding to the following formulae:

in which formulae: X represents an atom chosen from N, C, P and Si, R²²represents: an optionally substituted alkyl, acyl, aryl, alkene oralkyne group (i), or a saturated or unsaturated, optionally substitutedor aromatic carbon-based ring (ii), or a saturated or unsaturated,optionally substituted or aromatic heterocycle (iii), these groups andrings (i), (ii) and (iii) possibly being substituted with substitutedphenyl groups, substituted aromatic groups or groups: alkoxycarbonyl oraryloxycarbonyl (—COOR), carboxyl (—COOH), acyloxy (—O₂CR), carbamoyl(—CONR₂), cyano (—CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl,arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino,guanidimo, hydroxyl (—OH), amino (—NR₂), halogen, allyl, epoxy, alkoxy(—OR), S-alkyl, S-aryl, organosilyl, groups of hydrophilic or ionicnature such as the alkali metal salts of carboxylic acids, the alkalimetal salts of sulphonic acid, polyalkylene oxide (PEO or PPO) chainsand cationic substituents (quaternary ammonium salts), R representing analkyl or aryl group, Z, R^(21i) and R²³, which may be identical ordifferent, are chosen from: a hydrogen atom, an optionally substitutedalkyl, acyl, aryl, alkene or alkyne group, a saturated or unsaturated,optionally substituted or aromatic carbon-based ring, a saturated orunsaturated, optionally substituted heterocycle, alkoxycarbonyl oraryloxycarbonyl (—COOR), carboxyl (—COOH), acyloxy (—O₂CR), carbamoyl(—CONR₂), cyano (—CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl,arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino,guanidimo, hydroxyl (—OH), amino (—NR₂), halogen, allyl, epoxy, alkoxy(—OR), S-alkyl, S-aryl and organosilyl groups, R representing an alkylor aryl group, groups of hydrophilic or ionic nature such as the alkalimetal salts of carboxylic acids, the alkali metal salts of sulphonicacid, polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts), n>0, i ranges from 1 to n, p is equal to 0,1 or 2 depending on the valency of X, and also if X═C, then Z is not anS-alkyl or S-aryl group, the group R^(1i), where i=n, is not an S-alkylor S-aryl group, A represents a monoblock, diblock or triblock polymer.4. Latex according to claim 1, characterized in that the polymerizationis carried out in the presence of a polymer corresponding to thefollowing formula:

in which formula: X represents an atom chosen from N, C, P and Si, R³²represents: an optionally substituted alkyl, acyl, aryl, alkene oralkyne group (i), or a saturated or unsaturated, optionally substitutedor aromatic carbon-based ring (ii), or a saturated or unsaturated,optionally substituted or aromatic heterocycle (iii), these groups andrings (i), (ii) and (iii) possibly being substituted with substitutedphenyl groups, substituted aromatic groups or groups: alkoxycarbonyl oraryloxycarbonyl (—COOR), carboxyl (—COOH), acyloxy (—O₂CR), carbamoyl(—CONR₂), cyano (—CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl,arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino,guanidimo, hydroxyl (—OH), amino (—NR₂), halogen, allyl, epoxy, alkoxy(—OR), S-alkyl, S-aryl, organosilyl, groups of hydrophilic or ionicnature such as the alkali metal salts of carboxylic acids, the alkalimetal salts of sulphonic acid, polyalkylene oxide (PEO or PPO) chainsand cationic substituents (quaternary ammonium salts), R representing analkyl or aryl group, Z is chosen from: a hydrogen atom, an optionallysubstituted alkyl, acyl, aryl, alkene or alkyne group, a saturated orunsaturated, optionally substituted or aromatic carbon-based ring, asaturated or unsaturated, optionally substituted heterocycle,alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH), acyloxy(—O₂CR), carbamoyl (—CONR₂), cyano (—CN), alkylcarbonyl,alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido,maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH), amino(—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl andorganosilyl groups, R representing an alkyl or aryl group, groups ofhydrophilic or ionic nature such as the alkali metal salts of carboxylicacids, the alkali metal salts of sulphonic acid, polyalkylene oxide (PEOor PPO) chains and cationic substituents (quaternary ammonium salts),R³¹, which may be identical or different, are chosen from: a hydrogenatom, an optionally substituted alkyl, acyl, aryl, alkene or alkynegroup, a saturated or unsaturated, optionally substituted or aromaticcarbon-based ring, a saturated or unsaturated, optionally substitutedheterocycle, alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl(—COOH), acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN),alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl,phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH),amino (—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl andorganosilyl groups, R representing an alkyl or aryl group, groups ofhydrophilic or ionic nature such as the alkali metal salts of carboxylicacids, the alkali metal salts of sulphonic acid, polyalkylene oxide (PEOor PPO) chains and cationic substituents (quaternary ammonium salts),groups SR^(32,) n>0, A represents a monoblock, diblock or triblockpolymer.
 5. Latex according to claim 1, characterized in that thepolymerization is carried out in the presence of a polymer correspondingto the following formula: S═C(Z)-[C≡C]_(n)—S-[A]-R⁴¹  (IV) in whichformula: R⁴¹ represents: an optionally substituted alkyl, acyl, aryl,alkene or alkyne group (i), or a saturated or unsaturated, optionallysubstituted or aromatic carbon-based ring (ii), or a saturated orunsaturated, optionally substituted or aromatic heterocycle (iii), thesegroups and rings (i), (ii) and (iii) possibly being substituted withsubstituted phenyl groups, substituted aromatic groups or groups:alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl (—COOH), acyloxy(—O₂CR), carbamoyl (—CONR₂), cyano (—CN), alkylcarbonyl,alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido,maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH), amino(—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl,organosilyl, groups of hydrophilic or ionic nature such as the alkalimetal salts of carboxylic acids, the alkali metal salts of sulphonicacid, polyalkylene oxide (PEO or PPO) chains and cationic substituents(quaternary ammonium salts), R representing an alkyl or aryl group, Z,which may be identical or different, are chosen from: a hydrogen atom,an optionally substituted alkyl, acyl, aryl, alkene or alkyne group, asaturated or unsaturated, optionally substituted or aromaticcarbon-based ring, a saturated or unsaturated, optionally substitutedheterocycle, alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxyl(—COOH), acyloxy (—O₂CR), carbamoyl (—CONR₂), cyano (—CN),alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl,phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxyl (—OH),amino (—NR₂), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl andorganosilyl groups, R representing an alkyl or aryl group, groups ofhydrophilic or ionic nature such as the alkali metal salts of carboxylicacids, the alkali metal salts of sulphonic acid, polyalkylene oxide (PEOor PPO) chains and cationic substituents (quaternary ammonium salts),n>0, A represents a monoblock, diblock or triblock polymer.
 6. Latexaccording to claim 1, characterized in that the polymerization iscarried out in the presence of a polymer corresponding to the. followingformula: S═C(OR⁵¹)—S-[A]-R⁵²  (V) in which formula: R⁵¹ represents:

in which: R⁵³ and R⁵⁴, which may be identical or different, are chosenfrom halogen, ═O, ═S, —NO₂, —SO₃R, NCO, CN, OR, —SR, —NR₂, —COOR, O₂CR,—CONR₂ and —NCOR₂ groups with R representing a hydrogen atom or an alkylradical, alkenyl radical, alkynyl radical, cycloalkenyl radical,cycloalkynyl radical, aryl radical optionally fused to an aromatic ornon-aromatic heterocycle, alkylaryl radical, aralkyl radical orheteroaryl radical; these radicals may optionally be substituted withone or more groups, that may be identical or different, chosen fromhalogens, ═O, ═S, OH, alkoxy, SH, thioalkoxy, NH₂, monoalkylamino,dialkylamino, CN, COOH, ester, amide and CF₃ and/or optionallyinterrupted with one or more atoms chosen from O, S, N and P; or from aheterocyclic group optionally substituted with one or more groups asdefined above; or R⁵³ and R⁵⁴ form, together with the carbon atom towhich they are attached, a hydrocarbon-based ring or a heterocycle; R⁵³and R⁵⁶, which may be identical or different, represent a group asdefined above for R; or together form a C₂-C₄ hydrocarbon-based chain,optionally interrupted with a hetero atom chosen from O, S and N; R⁵²has the same definition as that given for R A represents a monoblock,diblock or triblock polymer.
 7. Latex according to any one of thepreceding claims, characterized in that polymer A corresponds to atleast one of the following formulae:

in which formulae: Va, V′a, Vb, V′b, Vc and V′c, which may be identicalor different, represent: H, an alkyl group or a halogen, Xa, X′a, Xb,X′b, Xc and X′c, which may be identical or different, represent H, ahalogen or a group R, OR, OCOR, NHCOH, OH, NH2, NHR, N(R)₂, (R)₂N⁺O⁻,NHCOR, CO₂H, CO₂R, CN, CONH₂, CONHR or CONR₂, in which R, which may beidentical or different, are chosen from alkyl, aryl, aralkyl, alkaryl,alkene and organosilyl groups, optionally perfluorinated and optionallysubstituted with one or more carboxyl, epoxy, hydroxyl, alkoxy, amino,halogen or sulphonic groups, l, m and n, which may be identical ordifferent, are greater than or equal to 1, x, y and z, which may beidentical or different, are equal to 0 or
 1. 8. Latex according to anyone of the preceding claims, characterized in that the polymer A has anumber-average molar mass of less than 20 000 and preferably less than10
 000. 9. Latex according to any one of the preceding claims,characterized in that the ethylenically unsaturated monomer(s) is (are)chosen from: CXdX′d(═CVd-CV′d)_(t)═CH₂ Xd and X′d, which may beidentical or different, represent: H, an alkyl group or a halogen, Vdand V′d, which may be identical or different, represent H, a halogen ora group R, OR, OCOR, NHCOH, OH, NH2, NHR, N(R)₂, (R)₂N+O⁻, NHCOR, CO₂H,CO₂R, CN, CONH₂, CONHR or CONR₂, in which R, which may be identical ordifferent, are chosen from alkyl, aryl, aralkyl, alkaryl, alkene andorganosilyl groups, optionally perfluorinated and optionally substitutedwith one or more carboxyl, epoxy, hydroxyl, alkoxy, amino, halogen orsulphonic groups, t is 0 or
 1. 10. Latex according to the preceding[lacuna], characterized in that the ethylenically unsaturated monomer(s)is (are) chosen from: styrene or its derivatives, butadiene,chloroprene, (meth)acrylic esters and vinyl nitrites.
 11. Latexaccording to any one of the preceding claims, characterized in that thepolymer containing residual ethylenically unsaturated bonds is obtainedby free-radical polymerization of at least one ethylenically unsaturatedmonomer chosen from: CXdX′d(═CVd-CV′d)_(t)═CH₂ Xd and X′d, which may beidentical or different, represent: H, an alkyl group or a halogen, Vdand V′d, which may be identical or different, represent H, a halogen ora group R, OR, OCOR, NHCOH, OH, NH2, NHR, N(R)₂, (R)₂N+O—, NHCOR, CO₂H,CO₂R, CN, CONH₂, CONHR or CONR₂, in which R, which may be identical ordifferent, are chosen from alkyl, aryl, aralkyl, alkaryl, alkene andorganosilyl groups, optionally perfluorinated and optionally substitutedwith one or more carboxyl, epoxy, hydroxyl, alkoxy, amino, halogen orsulphonic groups, t is 0 or
 1. 12. Latex according to any one of thepreceding claims, characterized in that the polymerization is carriedout by introducing the ethylenically unsaturated monomer and theinitiator into a solution of monoblock, diblock or triblock polymer. 13.Latex according to any one of claims 1 to 12, characterized in that thepolymerization is carried out by introducing in parallel theethylenically unsaturated monomer, the initiator and a solution ofmonoblock, diblock or triblock polymer.
 14. Latex according to any oneof claims 1 to 12, characterized in that the polymerization is carriedout by introducing the monoblock, diblock or triblock polymer and theinitiator into a suspension comprising the polymer containing residualethylenically unsaturated bonds.
 15. Redispersible powders that may beobtained by drying the latex of modified surface chemistry according toany one of claims 1 to
 14. 16. Powders according to the preceding claim,characterized in that the drying is performed in the presence of adrying adjuvant.
 17. Formulations intended for applications in thebuilding materials industry, comprising the latex with modified surfacechemistry according to any one of claims 1 to 14, or a redispersiblepowder obtained according to either of claims 15 and
 16. 18.Formulations intended for applications in the paints industry,comprising the latex with modified surface chemistry according to anyone of claims 1 to 13, or a redispersible powder obtained according toeither of claims 15 and
 16. 19. Formulations intended for applicationsin the adhesives and pressure-sensitive adhesives industry, comprisingthe latex with modified surface chemistry according to any one of claims1 to 14, or a redispersible powder obtained according to either ofclaims 15 and
 16. 20. Formulations intended for applications in thepaper industry, comprising the latex with modified surface chemistryaccording to any one of claims 1 to 14, or a redispersible powderobtained according to any either of claims 14 and
 16. 21. Use of a latexwith modified surface chemistry according to any one of claims 1 to 14,or of a redispersible powder obtained according to either of claims 15and 16, in formulations intended for applications in the buildingmaterials industry.
 22. Use of a latex with modified surface chemistryaccording to any one of claims 1 to 14, or of a redispersible powderobtained according to either of claims 15 and 16, in formulationsintended for applications in the paints industry.
 23. Use of a latexwith modified surface chemistry according to any one of claims 1 to 14,or of a redispersible powder obtained according to either of claims 15and 16, in formulations intended for applications in the adhesives andpressure-sensitive adhesives industry.
 24. Use of a latex with modifiedsurface chemistry according to any one of claims 1 to 14, or of aredispersible powder obtained according to either of claims 15 and 16,in formulations intended for applications in the paper industry.